1. Field of the Invention
The present invention relates to the field of the accessories for swimming activities. In particular, it relates to a new type of swimming goggles and the relevant manufacturing method.
2. Description of the Prior Art
The lenses of swimming goggles are mounted within a support frame which, unlike the diver masks, let the swimmer nose free. More precisely, the lenses are supported by bushes which are connected to the support frame through suitable flange means. The term xe2x80x9clensxe2x80x9d generally indicates, in the present description, the pair of substantially flat, transparent members placed before the swimmer eyes.
According to a widespread solution a lens and the respective bush are made of a single piece of transparent plastic material. In this way, besides the advantage of a light structure of the goggles, the advantage of a simple manufacture is also achieved, as the lens assembly can be produced with a single moulding operation. The generally used material is a mouldable thermoplastic material, such as polycarbonate, polyamide or polypropylene. The disadvantages of this type of solution consist in that the lenses made of the above materials easily mist over and become scratched.
In order to overcome to the above drawbacks, it has been proposed to make the lenses of glass, limiting the use of the thermoplastic material to the bushes. The glass has a melting temperature far higher than the moulding temperature of the plastic material, whereby the bush can be formed around the glass lens, which has been previously cut, shaped and inserted in the mould. The use of the glass, however, results in some not negligible drawbacks. First, glass has a relatively high specific weight with respect to any plastic material (generally, three times higher approximately), whereby the goggles are heavy. Furthermore, the accidental break of the goggles may result in a danger for the wearer.
When facing the above mentioned problems it has been unexpectedly found a solution which allows to fully mate lightness and safety requirements coming from the use of lenses made of plastic material to the anti-fogging and no-scratch properties typical of the glass lenses.
According to the invention, there are provided swimming goggles comprising a rigid frame for supporting a pair of glass-shaped transparent members, each formed by a flat lens and a flanged bush for the connection to the frame, the bushes being made of a mouldable thermoplastic material, characterized in that the flat lenses are made of a plastic material different from that of the bushes, having a softening temperature higher than the injection temperature of the material of the bushes, and having anti-fogging and/or no-scratch properties, the lenses being perimetrically fixed to the bushes within grooves formed on the respective bushes.
According to the invention there is also provided a method for manufacturing swimming goggles comprising a rigid frame for supporting a pair of glass-shaped transparent members, each consisting of a flat lens and a flanged bush for the connection to the frame, the bushes being formed in mouldable thermoplastic material, the essential feature of the method consisting in that the connection bushes are formed around the edge of the respective lenses which are made of a plastic material different from that of the bushes and with a softening temperature higher than the injection temperature of the material of the bushes said lenses being previously shaped and inserted inside the relevant mould.